(1) Field of the Invention
This invention relates, in general, to fire extinguishing sprinkler heads, and, in particular, to a concealed, automatic sprinkler head suitable for use in residential dwellings.
(2) Description of the Prior Art
Sprinkler systems are used extensively to provide automatic fire protection for residential, commercial and public buildings. Nevertheless, for a sprinkler head to qualify as suitable for use in a residential sprinkler system, the sprinkler head must pass many tests, several of which go beyond those normally used for ordinary commercial/industrial type sprinkler heads. The two greatest distinctions between ordinary and residential type sprinkler heads are the operating speed and specially designed water spray patterns that fire tests have revealed are necessary to combat or extinguish a fire in typical residences. The residential type sprinkler head must operate at a faster speed than the ordinary commercial/industrial sprinkler head, the faster the better, as the protection of human life is involved. Thus, there is a keen interest in providing residential sprinkler heads with even shorter times to become operable.
The primary purpose of a fire sprinkler system is to extinguish or, at least, contain a fire prior to the arrival of fire fighters and fire fighting apparatus. The theory behind the use of fire sprinkler systems is that, by preventing a fire from getting out of control, property damage is minimized and, even more importantly, in the case of residential sprinklers, lives can be saved.
At one time, the greatest danger from a fire in the home was in being trapped by flames and burned or suffocated by smoke. However, in more recent years, residential dwellings are being furnished with, or contain furnishings and fixtures which, because they are made of, or contain synthetic materials, give off highly toxic fumes when ignited or heated to a sufficient degree. Thus, it has become increasingly clear that many fire fatalities result from inhaling toxic fumes produced by the fire rather than from the fire itself or smoke produced thereby.
In many cases, fire victims are overcome by these toxic fumes and die in their sleep long before the fire becomes intense enough to be noticed by inhabitants of the dwelling or by neighbors. The recognition of this problem has led to the extensive use of heat and smoke alarms for alerting inhabitants of a dwelling that a fire is in progress. The early alert which is provided by these alarm systems enables the inhabitants to leave the dwelling while it is still safe to do so.
The use of smoke and heat detectors, however, does not diminish the importance of a fire sprinkler system. Although individual safety is of prime importance, the loss of one's home and worldly possessions, represents a tragic event. Also, a fire which is out of control represents, in some cases, a potential threat in spreading to adjacent property, thereby endangering the lives of other individuals. A fire out of control also represents a danger to fire fighters and to individuals who may not be able to leave a residential dwelling quickly, or perhaps not even at all, such as might be the case with small children, infants, the ill, handicapped persons, or elderly residents of a nursing home.
The automatic fire sprinkler head, whether of the commercial/industrial type or one for residential dwellings comprises, in general, an elongated body member which is open at one end, and connected to a water line, and is closed at the other end by a valve mechanism which operates to open in response to a fire. The valve mechanism ordinarily is maintained in the closed position, in part, by a low melting point fusible composition, until the occurrence of a fire. In such an occurrence, when the ambient temperature is increased to a predetermined level, the fusible composition melts, resulting in the valve mechanism operating to open from the closed position, and allowing the discharge of the fire extinguishing water.
In residential dwellings, and sometimes even in commercial buildings, it is most desirable to utilize a sprinkler head that can be located almost entirely above the ceiling so as to be hidden, or concealed, from view, leaving the attractiveness of a room relatively unspoiled. With some such sprinkler heads, the sprinkler head is concealed within the ceiling by a decorative plate which is mounted flush against the ceiling, the decorative plate itself being a part of the bottom of the sprinkler head. As described in U.S. Pat. Nos. 3,633,676 and 3,714,989, for example, the decorative plate is attached to the sprinkler head by a fusible material, and when the fusible material melts, the decorative plate is released to expose the fusible element of the lever assembly, which on melting releases the lever assembly to open the valve so that the fire extinguishing fluid can be discharged. Sprinkler heads of this type, as will be appreciated, have a disadvantage in that two separate fusible release mechanisms are required, one to release the decorative plate to expose the fusible element of the lever assembly, and the second to release the lever assembly to open the valve.
In U.S. Pat. No. 4,015,665, there is disclosed a further concealed, automatic sprinkler head, in which the flushmounted decorative plate, which is formed integrally with the latch bar of the sprinkler head, is provided with a series of openings. This, according to the patentee provides for improved heat transfer to the fusible element, resulting in a faster response rate in releasing the valve, to allow discharge of the fire extinguishing liquid. As is described in U.S. Pat. No. 4,015,665, the conical-shaped valve therein is connected to the ends of a pair of guide rods which are slidably mounted in holes in the sprinkler body. The valve assembly is normally retained in the closed position by a compression screw, which compresses a compression spring which exerts a downward force against the latch bar retaining the locking balls in place. In the event of a fire, the heat fusible material melts and the force of the compression spring, which is acting downwardly, causes release of the valve latching or locking mechanism. Thus, the force of the fire extinguishing water against the valve assembly causes it to drop whereby the outlet is opened and the fire extinguishing water is discharged against the deflector plate and onto the fire.